RFR 8203369 : Check for both EAGAIN and EWOULDBLOCK error codes

[Weijun Wang]

https://stackoverflow.com/questions/27509061/macro-to-avoid-duplicate-case-value

Someone has already used them in a switch expression...

> On May 25, 2018, at 12:45 PM, David Holmes <david.holmes at oracle.com> wrote:
> 
>>> I also wonder whether a smart compiler might not flag code where the errors do infact have the same value:
>>> 
>>> if (errno == 11 || errno == 11) ...
>>> 
>> At least gcc -O completely removes the second redundant test, so no observable changes is expected on supported platforms.
> 
> I'm more worried about a new compiler warning - especially if you happened to use them in a switch! - resulting in future build failures.